Our objective is to study pontine thermoregulatory mechanisms to understand their roles during wakefulness and during sleep. Specifically, we will study actual extent and structural organization of the pontine thermoregulatory areas. Furthermore, we will study whether the abolition of PS by lateral- caudal pontine lesions depends upon a heightened thermosensitivity of cats following such lesions rather a specific effect on PS generating mechanisms themselves. Thermoregulatory responses to different ambient temperatures will be studied in cats, before and after inactivating specific areas in the pontine tegmentum. The inactivation will be done by placement of electrolytic lesions or by injection of a cytotoxin (ibotenic acid). Cats will be chronically implanted to record EEG, EOG, EMG, core and subcutaneous temperatures. These studies will contribute to our knowledge of anatomical organization of pontine thermoregulatory areas and to our understanding of the brainstem control of thermoregulatory responses in a variety of physiological conditions such as sleep and wakefulness. In addition, knowledge of extrahypothalamic thermoregulatory areas eventually should contribute to our understanding of pathological alterations in body temperature which occur following damage or hemorrhage around the brainstem.